1 research outputs found
ClayâCarbon Nanotubes Hybrid Materials for Nanocomposite Membranes: Advantages of Branched Structure for Proton Transport under Low Humidity Conditions in PEMFCs
A new class of hybrid materials based
on carbon nanotubes (CNT)
rooted on smectite clays (SWy) was synthesized by catalytic chemical
vapor deposition (CCVD) method, and studied to be introduced in a
perfluorosulfonic acid (Nafion) membrane. Side-wall chemical oxidation
and organo-functionalization of the CNT was performed using organic
ester molecules containing hydrophilic groups (âRSO<sub>3</sub>H). SWyâCNT nanoadditives were incorporated in the polymer
by solution-precipitation method producing highly homogeneous nanocomposite
membranes with outstanding mechanical properties. Materials were characterized
by a combination of techniques (TGA, Raman, FT-IR, SEM, TEM, and DMA),
while a deep investigation on the water transport properties was performed
by NMR methods (PFG and relaxation times). Membranes containing SWyâoxCNTâRSO<sub>3</sub>H nanoadditives are able to guarantee a very high proton diffusion
in âquasi-anhydrousâ conditions. Proton mobility is
ensured by a correct network created from the long nanotubes (well
distributed through the clay nanoplatelets) appropriately functionalized
with acid groups. Remarkable are the electrochemical results: the
best membrane reaches conductivities of 7 Ă 10<sup>â2</sup> S cm<sup>â1</sup> at 120 °C and 30% RH, 1 order of magnitude
higher than pristine polymer, and a rather high value in the current
panorama of the PEMFCs